如何在后代元素上使用 .NET 自定义 ConfigurationElement 属性? [英] How do I use .NET custom ConfigurationElement properties on descendent elements?

问题描述

如何获取和使用在后代 CustomSetting 元素的父 ConfigurationSection 中设置的属性?当 CustomSetting 元素返回 Value 属性时，我需要这个属性.

How can I get and use an attribute set in the parent ConfigurationSection in the descendent CustomSetting element? I need this attribute when the CustomSetting element is returning the Value property.

我想像这样格式化 App.config:

I want to format the App.config like this:

<CustomSettings someProperty="foo">
    <CustomSetting key="bar" value="fermeneba" />
    <CustomSetting key="laa" value="jubaduba" />
</CustomSettings>

我的代码可以工作，只是我找不到从 CustomSetting 类访问 someProperty 属性的方法.到目前为止，我发现的唯一方法是像这样格式化配置，这很混乱:

I have the code working, except that I cannot find a way to access the someProperty attribute from the CustomSetting class. The only way that I've found, so far, is to format the configuration like this, which is messy:

<CustomSettings>
    <CustomSetting someProperty="foo" key="bar" value="fermeneba" />
    <CustomSetting someProperty="foo" key="laa" value="jubaduba" />
</CustomSettings>

推荐答案

实现这一点比应有的要困难得多，因为 System.Configuration API 不允许您从 ConfigurationElement 导航到它的父级.因此，如果您想访问父元素上的某些信息，您需要手动创建该关系.我已经为您问题中的配置片段汇总了一个示例实现:

Achieving this is more difficult than it should be since the System.Configuration API doesn't allow you to navigate from a ConfigurationElement to its parent. Hence, if you want to access some information that on a parent element you need to create that relationship manually. I've put together a sample implementation that does that for the config snippet in your question:

public class CustomSettingsSection : ConfigurationSection
{
    [ConfigurationProperty("someProperty", DefaultValue="")]
    public string SomeProperty
    {
        get { return (string)base["someProperty"]; }
        set { base["someProperty"] = value; }
    }

    [ConfigurationProperty("", IsDefaultCollection = true)]
    public CustomSettingElementCollection Elements
    {
        get 
        {
            var elements = base[""] as CustomSettingElementCollection;
            if (elements != null && elements.Section == null)
                elements.Section = this;
            return elements;
        }
    }
}

public class CustomSettingElementCollection : ConfigurationElementCollection
{

    internal CustomSettingsSection Section { get; set; }

    public override ConfigurationElementCollectionType CollectionType
    {
        get { return ConfigurationElementCollectionType.BasicMap; }
    }

    public CustomSettingElement this[string key]
    {
        get { return BaseGet(key) as CustomSettingElement; }
    }

    protected override ConfigurationElement CreateNewElement()
    {
        return new CustomSettingElement { Parent = this };
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return (element as CustomSettingElement).Key;
    }

    protected override string ElementName
    {
        get { return "customSetting"; }
    }
}

public class CustomSettingElement : ConfigurationElement
{

    internal CustomSettingElementCollection Parent { get; set; }

    public string SomeProperty
    {
        get
        {
            if (Parent != null && Parent.Section != null)
                return Parent.Section.SomeProperty;
            return default(string);
        }
    }




    [ConfigurationProperty("key", IsKey = true, IsRequired = true)]
    public string Key
    {
        get { return (string)base["key"]; }
        set { base["key"] = value; }
    }

    [ConfigurationProperty("value", DefaultValue = "")]
    public string Value
    {
        get { return (string)base["value"]; }
        set { base["value"] = value; }
    }

}

您可以看到 CustomSettingElementCollection 有一个 Section 属性，该属性在部分的 Elements 获取器中设置.CustomSettingElement 又具有 Parent 属性，该属性在集合的 CreateNewElement() 方法中设置.

You can see that the CustomSettingElementCollection has a Section property which gets set in the section's Elements getter. The CustomSettingElement, in turn, has a Parent property which gets set in the collection's CreateNewElement() method.

这样就可以向上遍历关系树并向元素添加 SomeProperty 属性，即使该属性与该元素上的实际 ConfigurationProperty 不对应.

That then makes it possible to walk up the relationship tree and to add a SomeProperty property to the element even though this one doesn't correspond to an actual ConfigurationProperty on that element.

希望能让您知道如何解决您的问题！

Hope that gives you an idea how to solve your problem!

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